屠宰週齡對大體型閹雞生長性能、肌肉組成及品質之影響

Effect of slaughter age on growth performances, muscle compositions and quality of heavy type caponized native chickens

林正鏞(Cheng-Yung Lin) ； 許振忠(Jenn-Chung Hsu)

《畜產研究》 50卷1期 (2017/03) Pp. 1-6

摘要

本試驗旨在探討屠宰週齡對大體型閹公雞肌肉組成、物理性質及感官品評之影響。試驗選用13週齡去勢之大體型閹公雞（竹北仿土雞）594隻，雞隻採平飼，91－126日齡（13－18週齡）餵給含蛋白質18%、代謝能3,200 kcal/kg之飼糧，127－217日齡（18－31週齡），餵給含蛋白質15%、代謝能2,800 kcal/kg之飼糧。試驗期間水與飼料採任食，每天給予23小時光照。從25週齡起每隔一週秤重及屠宰36隻，至31週齡止，測定生長性能、肌肉組成、物理性質及感官品評等性狀。結果顯示，大體型閹雞之增重可持續至29週齡，之後會失重，且飼料轉換率隨週齡增加而變差。28週齡以前屠宰之雞隻胸肉水分含量顯著（P＜0.05）較29週齡以後屠宰之雞隻高；胸肉脂肪含量、蒸煮失重、彈性與咀嚼性隨週齡增加而增加，而蛋白質含量則隨週齡增加而降低；胸肉內聚性以30週齡屠宰之雞隻顯著（P＜0.05）較其他週齡屠宰之雞隻低，28週齡屠宰之雞隻肌肉風味感官品評顯著（P＜0.05）較25及31週齡屠宰之雞隻差，嫩度感官品評以29週齡以後屠宰之雞隻顯著（P＜0.05）較27週齡以前屠宰之雞隻差，多汁性感官品評以27週齡屠宰之雞隻顯著（P＜0.05）較28週齡以後屠宰之雞隻佳，總接受性感官品評以25及27週齡屠宰之雞隻顯著（P＜0.05）較28及29週齡屠宰之雞隻佳。由本試驗之結果觀之，大體型閹公雞於27週齡屠宰即可獲得良好之肌肉品質，如考慮利潤飼養期最好不要超過29週齡。

關鍵字

大體型閹雞 ； 屠宰週齡 ； 生長性能 ； 肌肉品質

並列摘要

An experiment was carried out to determine the effects of slaughter age on muscle compositions, physical properties and eating quality of heavy type caponized native chickens. A total of five hundred and ninety-four cockerels were surgically caponized at 13 weeks of age. Capons reared in floors were fed diets containing 18% crude protein and 3,200 kcal/kg metabolizable energy during from 91 to 126 days old and fed diets containing 15% crude protein and 2,800 kcal/ kg metabolizable energy during from 127 to 217 days old. Feed and water were provided ad libitum. Incandescent light was provided 23 hours per day during experimental period. Birds were slaughtered from 25 weeks of age through 31 weeks of age with 1 week interval, which were slaughtered thirty-six birds in each week. The growth performances, muscle compositions, physical properties and taste panel scores were used as criteria for the determination of the optimum slaughter age of heavy type caponized native chickens. The results indicated that the accumulation body weight gain reached peak at 29 weeks of age and declined at 30 weeks of age. Besides, the feed conversion of capons, dropped significantly (P ＜ 0.05) with the advance of age. Furthermore, the moisture content of breast muscle of birds before 28 weeks of age were higher (P ＜ 0.05) than those of birds after 29 weeks of age. In addition, the fat content, cooking loss, elasticity and chewiness of breast muscle increased and the protein content of breast muscle decreased with the increase of slaughter age. Therefore, the breast muscle cohesiveness of birds was lower (P ＜ 0.05) at 30 weeks of age than birds at 26, 28, 29 and 31 weeks of age. Accordingly, the sensory panel scores for breast muscle flavor of birds were higher (P ＜ 0.05) at 28 weeks of age than those of birds at 25 and 31 weeks of age. Also, the sensory panel scores for breast muscle tenderness were lower (P ＜ 0.05) after 29 weeks of age birds than those before 27 weeks of age birds. However, after 28 weeks of age birds had lower (P ＜ 0.05) sensory panel scores for breast muscle juiciness than birds at 27 weeks of age birds. In addition, the sensory panel scores for breast muscle overall-acceptance of birds were higher (P ＜ 0.05) at 25 and 27 weeks of age than those of birds at 28 and 29 weeks of age birds. Moreover, our findings also indicate that slaughtering at 27 weeks old of could reach excellent meat quality and the optimal age to market was no more than 29 weeks of age for heavy type caponized native chickens.

並列關鍵字

Heavy type capons ； Slaughter age ； Growth performance ； Meat quality